Rivers (Flashcards)

• What is suspension?


  Fine, light material which is carried along by the river downstream.
• What is traction?


  Large boulders are rolled along the riverbed. (Aren't carried by water.)
• What is saltation?


  Small pebbles are bounced along the riverbed.
• What is a solution?


  Minerals chemically dissolved in water.
• What is hydraulic action?


  Water forced into cracks of river banks and beds.
• What is abrasion? (also known as corrosion.)


  Small boulders scratching their way down, causing the wearing down of riverbanks.
• What is attrition?


  When rough stones collide with each other, becoming smoother and rounder.
• What does a hydrograph plot?


  The river discharge after a storm.
• What is lag time in a hydrograph?


  The time interval between the peak rainfall and the peak discharge.
• What does a flashy hydrograph consist of?


  high peak

  high density (faster water transfer)

  steep slopes

  heavy rainfall intensity

  impermable rocks
• What does a low, flat hydrograph consist of?


  low peak

  low density (slower water transfer)

  gentle slopes

  light rainfall intensity

  permable rocks
• What is a drainage basin?


  Area of land drained by a river and its' tributaries.
• What is a river source?


  The start of a river.
• What is a tributary?


  A small stream which joins a larger river.
• What is the mouth of a river?


  The end of a river, where it meets the sea.
• What is a watershed?


  The edge of a river basin.
• What is an estuary?


  Fresh water which meets the salty sea, just before the mouth.
• What is an interlocking spur?


  Found in upper course

  Formed by erosion

  Projections of high land

  Found on each side of valley
• What is a v-shaped valley?


  Formed by vertical erosion

  When the river tries to reach the sea as fast/early as possible.
• What is in the first stage of forming a waterfall?


  Soft rocks are downstream of harder rocks

  Plunge pool is formed

  Made by hydraulic action
• What happens in the second stage of forming a waterfall?


  Overhang formed due to the soft rocks being eroded

  Small rocks scratch their way down the river (abrasion occurs)
• What happens in the third stage of forming a waterfall?


  Overhang of hard rock collapses (into plunge pool)

  Waterfall moves back
• What is a long profile?


  Line that represents change from the source to the mouth.
• What are characteristics of the upper section of a long profile?


  Steep gradient

  Vertical erosion

  Waterfalls

  V-shaped valleys
• What are characteristics of the middle section of a long profile?


  Deeper and wider river

  Vertical and lateral erosion

  Velocity increases

  Meanders form
• What are characteristics of the lower section of a long profile?


  Channel is the widest and deepest

  Lower gradient

  Round sediment
• What is a levee?


  A raised embankment built along a river or other body of water to prevent flooding.
• What is an ox-bow lake?


  A lake that is made from a cut-off meander. It is separated from the main river by deposits of material.
• What is a gorge?


  A deep narrow passage with a rocky walls and a river running between them. Made from the backwards retreat of waterfall.
• What is deposition?


  The process of sediment being laid down.
• What is runoff?


  When water washes off quickly.

  Rainfall that does not get absorbed by the soil.